Vehicle liftgate power operating system

Abstract

A power operating system for opening and closing a vehicle liftgate has a pair of drive units supported on the respective vehicle pillars at the sides of the liftgate opening. Each drive unit includes a vertically oriented channel and a rack member that moves in the channel. The rack member comprises a rack bar and a plurality of rack links that are pivotally connected end-to-end. A transfer link is universally attached to the rack bar at one end and universally attached to the liftgate at the opposite end. The rack member is raised and lowered by a power unit that has a motor driven pinion gear that meshes with teeth of the rack bar and the rack links in succession. Raising and lowering the rack member opens and closes the liftgate via the transfer link.

We claim:  
     
       1. A power operating system for opening and closing a vehicle liftgate that is pivotally attached to an aft end of a vehicle roof for pivotal movement between an open position and a closed position about a generally horizontal hinge axis comprising: 
       an annular channel having a linear upper portion and a curved lower portion, the linear upper portion having a longitudinal slot in a side wall of the annular channel and a window in the side wall of the annular channel disposed opposite the longitudinal slot,  
       a rack member disposed in the channel for movement in the channel, the rack member comprising a rack bar and a plurality of rack links that are pivotally connected end to end to form a chain that is pivotally connected to the rack bar,  
       the rack bar having a stud that extends through the longitudinal slot in the side wall of the annular channel,  
       the rack bar and the plurality of rack links having teeth facing the window in the side wall of the annular channel,  
       a transfer link having an end that is universally connected to the stud,  
       the transfer link having an opposite end that is universally attached to the liftgate at a location spaced from the hinge axis, and  
       a power unit having an output pinion gear meshing with teeth of the rack bar and the plurality of rack links in succession for moving the rack member in the annular channel between a first position holding the vehicle liftgate in the open position and a second position holding the vehicle liftgate in the closed position.  
     
     
       2. The power operating system as defined in  claim 1  wherein the power unit is secured to the annular channel and comprises an electric motor that drives the output pinion gear via an electromagnetic clutch. 
     
     
       3. The power operating system as defined in  claim 1  wherein the linear upper portion of the annular channel is disposed in the vehicle in a vertical orientation. 
     
     
       4. A vehicle having a vehicle liftgate that is pivotally attached to an aft end of a vehicle roof for pivotal movement between an open position and a closed position about a generally horizontal hinge axis and a power operating system for opening and closing the vehicle liftgate, the power operating system comprising: 
       a rectangular channel fixed to the vehicle at a pillar of the vehicle in a vertical orientation,  
       the rectangular channel having a linear upper portion and a curved lower portion, the linear upper portion having a longitudinal slot in a side wall of the rectangular channel and a window in an opposite side wall of the rectangular channel,  
       rack member disposed in the channel for movement in the channel, the rack member comprising a rack bar and a plurality of rack links that are pivotally connected end to end to form a chain that is pivotally connected to the rack bar,  
       the rack bar having a stud that extends through the longitudinal slot in the side wall of the channel,  
       the rack bar and the plurality of rack links having teeth facing the window in the opposite side wall of the channel,  
       a transfer link having an end that is universally connected to the stud,  
       the transfer link having an opposite end that is universally attached to the liftgate at a location spaced from the hinge axis,  
       a power unit having an output pinion gear meshing with teeth of the rack bar for moving the rack bar in the channel between a first position holding the vehicle liftgate in the open position and a second position holding the vehicle liftgate in the closed position.  
     
     
       5. The power operating system as defined in  claim 4  wherein the power unit is secured to the an outboard side wall of the channel and comprises an electric motor that drives the output gear via an electromagnetic clutch. 
     
     
       6. A vehicle having a vehicle liftgate that is pivotally attached to an aft end of a vehicle roof for pivotal movement between an open position and a closed position about a generally horizontal hinge axis and a power operating system for opening and closing the vehicle liftgate, the power operating system comprising: 
       a rectangular channel having a linear upper portion and a curved lower portion, the linear upper portion having a longitudinal slot in a side wall of the rectangular channel that faces rearwardly toward the liftgate,  
       the rectangular channel having a window in an opposite side wall of the rectangular channel that faces forwardly away from the liftgate,  
       a rack member disposed in the channel for movement in the channel,  
       the rack member comprising a rack bar and a plurality of rack links that are pivotally connected end to end to form a chain that is pivotally connected to the rack bar,  
       the rack bar having a stud that extends through the longitudinal slot in the side wall of the channel,  
       the rack bar and the plurality of rack links having teeth facing the window in the opposite side wall of the channel,  
       a transfer link having a first socket at one end that is universally connected to the stud,  
       the transfer link having a second socket at an opposite end that is universally attached to a second stud attached to the liftgate at a location spaced from the hinge axis,  
       a power unit having an output pinion gear that projects into the window of the channel and meshes with the teeth of the rack bar for moving the rack bar in the rectangular channel between a first position holding the vehicle liftgate in the open position and a second position holding the vehicle liftgate in the closed position, and  
       a rectangular channel fixed to the vehicle at a rear pillar of the vehicle so that the linear upper portion is in a vertical orientation.  
     
     
       7. The power operating system as defined in  claim 6  wherein the power unit is secured to an outboard side wall of the rectangular channel and comprises an electric motor that drives the output gear via an electromagnetic clutch. 
     
     
       8. The power operating system as defined in  claim 6  wherein the first socket is open in a longitudinal direction of the vehicle and the second socket is open in a transverse direction of the vehicle. 
     
     
       9. The power operating system as defined in  claim 6  wherein the rack bar has at least one shoe of low friction material at a leading end. 
     
     
       10. The power operating system as defined in  claim 6  wherein the curved lower portion of the rectangular channel curves in a longitudinal direction of the vehicle. 
     
     
       11. A power operating system for opening and closing a vehicle liftgate that is pivotally attached to an aft end of a vehicle roof for pivotal movement between an open position and a closed position about a generally horizontal hinge axis comprising: 
       an annular channel having a linear upper portion and a curved lower portion, the linear upper portion having a longitudinal slot in a side wall of the annular channel and a window in the side wall of the annular channel disposed opposite the longitudinal slot,  
       a flexible member disposed in the channel for movement in the channel, the flexible drive member comprising a plurality of links that are pivotally connected end to end to form a chain,  
       one of the plurality of links having a stud that extends through the longitudinal slot in the side wall of the annular channel,  
       a transfer link having an end that is universally connected to the stud,  
       the transfer link having an opposite end that is universally attached to the liftgate at a location spaced from the hinge axis, and  
       a power unit having an output member engaging the plurality of links in succession via the window for moving the flexible drive member in the annular channel between a first position holding the liftgate in the open position and a second position holding the vehicle liftgate in the closed position.  
     
     
       12. The power operating system as defined in  claim 11  wherein the power unit is secured to the annular channel and comprises an electric motor that drives the output member via an electromagnetic clutch. 
     
     
       13. The power operating system as defined in  claim 11  wherein the linear upper portion of the annular channel is disposed in the vehicle in a vertical orientation. 
     
     
       14. The power operating system as defined in  claim 11  wherein the annular channel has a side wall that faces inboard and the longitudinal slot is in the side wall of the annular channel that faces inboard.